Generally, ships are water transportation means for transporting people, various cargo, and the like. The ships are constructed to be propelled and steered by way of a propelling power, which is obtained as screws of the ship, immersed under water, rotate to expel the water upon receiving a driving force transmitted from a power source through transmission shafts. The power source for the ships is selected from among an internal combustion engine, steam engine, electric motor, and the like.
Conventionally, the screws connected to the power source, namely, motor through the transmission shafts are located at the stern of the hull of the ship, and adapted to propel the ship forward or backward while rotating using the driving force of the motor. During rotation, the screws further cause steering plates installed at the stern of the ship to operate, so as to vary traveling directions of the ship. Such screws and steering plates are controlled from a steering house or the like, and the traveling direction and speed of the ship are determined according to the rotation direction and speed of the screws.
In case of the conventional ships as stated above, they should be principally propelled by rotation energy of the screws caused by the motor as well as water current energy. The water current energy is generated as the rotating screws expel the water thus generating backward water currents. The generated water currents, however, are actually dissipated without affecting the propulsion of the ship. Therefore, the conventional ships have a difficulty of increasing their propelling power beyond a predetermined value.
As another problem of the conventional ships, although they are streamlined in order to reduce a friction coefficient for achieving innovation of their structure, there is a limitation in effectively reducing the friction coefficient and a risk of massive waves, which are generated by the water expelled during traveling of the ship. For reference, waves generated when a naval destroyer travels at thirty-eight knots (about seventy kilometers an hour) considerably affect locations up to and beyond one kilometer away.
As can be seen from the above description, since the conventional ships are considerably affected by a frictional resistance, in order to prevent deterioration of the speed thereof, it is necessary to make special studies of both the hull shape of the ship and a high-horsepower engine.
In order to solve the above-mentioned problems, many studies have been developed with relation to propulsion devices for the ships. As one example, a Korean Patent Laid-open Publication No. 2000-0039958 discloses a hydraulic driven type propulsion device for use in a ship, which is attached to the stern wall of the ship and has a structure and function for simply performing forward and backward movements of a propeller thereof. Considering the structure of the disclosed propulsion device in detail, it comprises a closed type hydraulic system circuit configured in such a way that a hydraulic pressure is generated as a hydraulic pump is driven by a high-speed diesel engine of less than 350 horsepower, and the generated hydraulic pressure is supplied to a hydraulic motor, which is installed within a body of the propulsion device and directly connected to the propeller so as to operate it. According to the closed type hydraulic system circuit, it is possible to achieve a high-pressure and high-speed operation so that an operating hydraulic pressure reaches 250 atmospheres and the revolutions per minute of the hydraulic motor reaches 2500 rpm, and consequently to adjust an inclination angle of the hydraulic pump within a range of 90° upward and downward at a remote place, resulting in a control in the flow of operating fluid. The disclosed propulsion device, however, has a disadvantage in that the overall structure thereof is complex, and it has no function for increasing the propelling power thereof by the use of water surface tension and water resistance.
As another example, Korean Patent Laid-open Publication No. 1999-0038271 discloses a ship having a leakage oil collection function using water wheels. In this disclosed ship, both at the stem and stern of the hull are installed water wheels through shafts. The water wheels are formed at their outer peripheral surfaces with outwardly protruding blades and adapted to obtain the buoyancy of the hull and a thrust force as they rotate upon receiving a driving force of the ship. Here, one of the water wheels installed at the stem of the hull serves to provide a steering ability using a steering device, and the tube-shaped outer peripheral surfaces of the water wheels are further formed with brushes, in addition to the blades, so as to adsorb leakage oil. The adsorbed oil is removed by a scrapper and collected in an oil storage tank. The disclosed Korean Patent Laid-open Publication No. 1999-0038271 is somewhat similar to the present invention in that it achieves a propelling power thereof by using the water wheels formed with the blades. However, the disclosed invention does not express an important outstanding feature caused from a link belt of the present invention wherein the link belt is installed to wholly surround around the water wheels and adapted to be accelerated by water resistance and water surface tension, as opposed to being conventionally connected and propelled by a propulsion device.